Lens apparatus and imaging apparatus

ABSTRACT

A lens apparatus includes a tripod mount, a cylindrical member supported rotatably around an optical axis on the tripod mount, a roller housed in the tripod mount and including a rolling bearing and a shaft member engaged with the rolling bearing, a roller holding member configured to rotatably hold the roller, and a biasing member configured to bias the roller against the cylindrical member via the roller holding member.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a lens apparatus and an imagingapparatus having a tripod mount.

Description of the Related Art

A conventional lens apparatus has a revolving mechanism for rotating alens barrel around the optical axis in an optical system. For example, alens apparatus having a tripod mount can easily change the longitudinaland lateral composition by rotating the lens and the camera around theoptical axis while the tripod mount is fixed onto the tripod.

The revolving mechanism includes a portion (simply referred to as a“click” hereinafter) that provides a click feeling for each specificrotation phase so that the user can recognize the rotational position ofthe lens through the click feeling. In particular, the lens apparatushaving the tripod mount includes click portions in the gravity directionwhen the lens apparatus is horizontally attached to the tripod, andoften provides clicks for every 90° phase. In general, the click feelingis provided by biasing a ball, a pin, a roller or the like pressed by abiasing member on the fixed part side, such as the tripod mount, againsta recessed groove provided on the lens body side.

Japanese Patent Laid-Open No. (“JP”) 2012-47898 discloses a lensapparatus that can adjust the click position in revolving.

The lens apparatus disclosed in JP 2012-47898 ca bias the rollersupported on the tripod mount unit against the lens apparatus bodythrough a biasing spring, and the outer circumferential surface of theroller contacts the lens apparatus body and a washer member. Hence,depending on the biasing force of the biasing spring, when the lensapparatus body is revolved relative to the tripod mount unit, the rollerslides without rotating relative to the lens apparatus body. The rollersliding on the lens apparatus body is likely to wear the lubricatingcoating applied to the contact portion with the roller in the lensapparatus body and the contact component. Repetitive revolving willgenerate the abrasion powder through abrasions, peel the lubricatingcoating, and degrade the operability such as the feeling and torque inthe revolving.

SUMMARY OF THE INVENTION

The present invention provides a lens apparatus and an imaging apparatushaving a revolving mechanism with an improved durability.

A lens apparatus according to one aspect of the present inventionincludes a tripod mount, a cylindrical member supported rotatably aroundan optical axis on the tripod mount, a roller housed in the tripod mountand including a rolling bearing and a shaft member engaged with therolling bearing, a roller holding member configured to rotatably holdthe roller, and a biasing member configured to bias the roller againstthe cylindrical member via the roller holding member.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are sectional views of a principal part in a lensapparatus according to a first embodiment.

FIG. 2 is an exploded perspective view of the lens apparatus accordingto the first embodiment.

FIG. 3 is a sectional view of a principal part in a lens apparatusaccording to a second embodiment.

FIG. 4 is a structural view of an imaging apparatus according to a thirdembodiment.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a description will be givenof embodiments according to the present invention.

First Embodiment

Referring now to FIG. 2, a description will be given of a lens apparatus(lens barrel) according to a first embodiment of the present invention.FIG. 2 is an exploded perspective view of the lens apparatus 100. Thelens apparatus 100 is an interchangeable lens attachable to anddetachable from the imaging apparatus body.

The lens apparatus 100 includes a barrel body 10 configured to hold anoptical system (lens), and a tripod mount unit 20 configured to supportthe barrel body 10 integrally with a camera (imaging apparatus body,camera body) so that the barrel 10 can rotate at a fixed position. Thelens barrel body 10 includes a mount member 11 for detachably attachingthe lens apparatus 100 to the camera. The mount member 11 is fixed ontoan exterior ring (cylindrical member) 12 rotatably supported around anoptical axis OA on the tripod mount 22 by a screw or the like.

The tripod mount unit 20 includes a tripod mount ring unit 21 and atripod mount 22 having a screw portion 22 a (see FIG. 1A) engaged with atripod screw. The tripod mount ring unit 21 includes a tripod mount ring23 having a diameter engagement portion with the exterior ring 12, and alock knob 24 attached to the tripod mount ring 23. The tripod mountingring 23 has a roller housing portion 23 a. The roller housing portion 23a houses a roller 25, a roller holding member 26, a biasing member 27, aguide member 28, and a press plate 29 (see FIG. 1B). This will bedescribed in detail later.

In incorporating the tripod mount unit 20 into the barrel body 10, thetripod mount ring unit 21 is first inserted from the backside (imageside) of the barrel body 10, and the roller 13 is inserted into the holeportion 23 b in the tripod mount ring 23 (See FIG. 1B) at apredetermined position. The roller 13 is screwed onto the exterior ring12. At least three rollers 13 are provided, and the tripod mounting ringunit 21 is rotated, incorporated at a predetermined phase, and fixedonto the exterior ring 12. The tripod mounting ring 23 has an engaginggroove 23 c for the roller 13 and the engaging groove 23 c determinesthe position of the tripod mount ring unit 21 in the optical axisdirection. Next, the tripod mount 22 is fixed onto the tripod mount ringunit 21 by a screw 30. Thereby, the tripod mount unit 20 is completelyincorporated into the barrel body 10.

When the screw portion 22 a of the tripod mount 22 is fixed onto thetripod screw, the barrel body 10 becomes rotatable at a fixed positionrelative to the tripod mount unit 20. Thereby, an image can be capturedwhile the camera is revolved. A relative rotation between the lensbarrel body 10 and the tripod mount unit 20 can be suppressed byfastening the lock knob 24.

Referring now to FIGS. 1A and 1B, a description will be given of theroller housing portion 23 a in the tripod mounting ring 23. FIG. 1A is asectional view of principal part in the lens apparatus 100, and FIG. 1Bis an enlarged view of an area A in FIG. 1A. As illustrated in FIG. 1B,the roller 25 includes a shaft member 25 a, a rolling bearing 25 b, anda spacer 25 c. The shaft member 25 a is engaged with the groove portion26 a on the roller holding member 26. The roller holding member 26contacts the biasing member 27 and the biasing force biases the roller25 against the exterior ring 12. The roller holding member 26 is engagedwith the guide member 28 and guided so as to move back and forth in adirection (vertical direction in FIG. 1B) corresponding to the biasingdirection of the biasing member 27. The biasing member 27 also contactsthe holding plate 29, and is fixed by fastening the holding plate 29 andthe guide member 28 with the tripod mount ring 23 by a screw 31together. Thereby, the roller 25 is housed in the roller housing portion23 a of the tripod mounting ring 23.

The shaft member 25 a in the roller 25 is engaged with the inner ring ofthe rolling bearing 25 b, contacts the contact portion 26 b in theroller holding member 26, and receives the biasing force from thebiasing member 27. The outer ring of the rolling bearing 25 b in theroller 25 is forced against the exterior ring 12 under the biasing forceof the biasing member 27. In other words, the biasing force of thebiasing member 27 acts between the shaft member 25 a and the contactportion 26 b of the roller holding member 26, between the inner ring ofthe shaft member 25 a and the rolling bearing 25 b, and between theouter ring of the rolling bearing 25 b and the exterior ring 12.

As the lens barrel body 10 is rotated relative to the tripod mount unit20, the roller holding member 26 receives the shaft member 25 a of theroller 25 and thus the frictional force applied to the outer ring of therolling bearing 25 b becomes small. Therefore, the exterior ring of therolling bearing 25 b reliably rotates without slipping on the exteriorring 12. This configuration can prevent the abrasion powder from beinggenerated by the slippage between the exterior ring and the roller.Hence, a lens apparatus with an enhanced durability in revolving can beprovided.

A rolling contact surface 12 a on the exterior ring 12 with the roller25 has a plurality of concave (or recessed) portions 12 b. When the lensbarrel body 10 is rotated relative to the tripod mount unit 20, theroller 25 falls into the concave portion 12 b, is biased against, andcontacts a chamfered portion of the concave portion 12 b. Thereby, theuser can obtain a click feeling. For example, the concave portion 12 bhas a phase for obtaining a click feeling and a phase shifted by 90°from the phase when the camera (or the lens barrel body 10) ishorizontal to the tripod mount unit 20. Thereby, the user can easilyswitch between image capturing in the normal state and so-called imagecapturing at a vertical position.

This embodiment receives the biasing force from the biasing member 27 atboth ends of the shaft member 25 a and the roller holding member 26.Hence, when the roller 25 falls into the concave portion 12 b, theroller 25 is prevented from contacting the chamfered portion of theconcave portion 12 b while the shaft of the roller 25 is inclined.Therefore, since a load is uniformly applied to the contact surfacebetween the roller 25 and the chamfered portion of the concave portion12 b, the contact surface can be prevented from being worn.

According to this embodiment, the roller holding member 26 has an Hshape on a section (illustrated in FIG. 1B) including the optical axisOA in the lens. The roller holding member 26 has a first concave portion26 c and a second concave portion 26 d, and at least part of the rollingbearing 25 b is disposed inside the first concave portion 26 c, and atleast part of the biasing member 27 is disposed inside the secondconcave portion 26 d. This configuration increases the contact areabetween the roller holding member 26 and the guide member 28 that guidesthe roller holding member 26 along the vertical direction in FIG. 1B,and makes compact the (vertical size) of the tripod mounting ring 23.

Second Embodiment

Referring now to FIG. 3, a description will be given of a lens apparatus(lens barrel) according to a second embodiment of the present invention.FIG. 3 is a sectional view of principal part of the lens apparatusaccording to this embodiment.

In the lens apparatus according to the first embodiment, the shaftmember 25 a in the roller 25 is engaged with the roller holding member26, and the rolling bearing 25 b rolls on the exterior ring 12. On theother hand, in the lens apparatus according to this embodiment, theroller bearing 32 b in the roller 32 is engaged with the roller holdingmember 26, and the roller body 32 a rolls on the exterior ring 12. Thoseelements having the same functions or roles in this embodiment as thosein the first embodiment are designated by the same reference numerals,and a description thereof will be omitted.

FIG. 3 is a sectional view near the exterior ring 12 and the rollerhousing portion 23 a in the tripod ring 23, and similar to the firstembodiment, the roller housing portion 23 a houses a roller 32, a rollerholding member 26, a biasing member 27, a guide member 28, and a holdingplate 29. The roller 32 includes a shaft member 32 a as a roller bodyand a rolling bearing 32 b, and both ends of the shaft member 32 a(shaft portions at both ends of the roller body) and the inner ring inthe rolling bearing 32 b are engaged with each other. The outer ring inthe rolling bearing 32 b is engaged with the groove portion 26 a of theroller holding member 26, contacts the contact portion 26 b of theroller holding member 26, and receives the force from the biasing member27. Hence, the biasing force from the biasing member 27 acts between theexterior ring in the rolling bearing 32 b and the contact portion 26 bin the roller holding member 26, between the inner ring in the rollingbearing 32 b and the shaft member 32 a, and between the shaft member 32a and the exterior ring 12.

When the lens barrel body 10 is rotated relative to the tripod mountunit 20 in this state, the frictional force acting the roller body 32 ais small because the roller holding member 26 receives the rollingbearing 32 b of the roller 32 and the inner ring in the rolling bearing32 b and the shaft portions at both ends of the roller body 32 a areengaged with each other. The roller body 32 a reliably rotates withoutslipping relative to the exterior ring 12. Similar to the firstembodiment, this configuration can prevent from being generated theabrasion powder caused by the slippage between the exterior ring and theroller. Hence, a lens barrel with an enhanced durability of revolvingcan be provided.

Third Embodiment

Referring now to FIG. 4, a description will be given of an imagingapparatus according to a third embodiment of the present invention. FIG.4 is a configuration diagram of an imaging apparatus 200 (single-lensreflex camera). In FIG. 4, the lens apparatus 100 (interchangeable lens)includes an imaging optical system 1 (lens unit). The camera body 120(imaging apparatus body) includes a quick return mirror 3, a focusscreen 4, a Penta roof prism 5, an eyepiece lens 6, and the like. Thequick return mirror 3 upwardly reflects a light flux formed via theimaging optical system 1. The focus screen 4 is disposed at the imageforming position of the imaging optical system 1. The Penta roof prism 5converts an inverse image formed on the focus screen 4 into an erectimage. The user can observe the erect image through the eyepiece 6.

An image sensor 7 includes a CCD sensor and a CMOS sensor,photoelectrically converts an optical image (object image) formed viathe imaging optical system 1, and outputs image data. In imagecapturing, the quick return mirror 3 is retracted from the optical path,and an optical image is formed on the image sensor 7 via the imagingoptical system 1. A control unit 110 has a CPU and controls theoperation of each unit of the imaging apparatus 200.

The imaging apparatus 200 includes, but is not limited to, the camerabody 120 having the image sensor 7 and the lens apparatus 100 detachablyattached to the camera body 120. It may be an imaging apparatus in whicha camera body and a lens apparatus are integrated with each other, or amirrorless single-lens reflex camera (mirrorless camera) having no quickreturn mirror.

Each embodiment can provide a lens barrel and an imaging apparatus withan enhanced durability of the revolving mechanism.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2017-234296, filed on Dec. 6, 2017, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A lens apparatus comprising: a tripod mount; acylindrical member supported rotatably around an optical axis on thetripod mount; a roller housed in the tripod mount and including arolling bearing and a shaft member engaged with the rolling bearing; aroller holding member configured to rotatably hold the roller; and abiasing member configured to bias the roller against the cylindricalmember via the roller holding member.
 2. The lens apparatus according toclaim 1, wherein the rolling bearing contacts the cylindrical member,and the shaft member contacts the roller holding member.
 3. The lensapparatus according to claim 2, wherein a biasing force of the biasingmember acts between the shaft member and a contact member of the rollerholding member, between the shaft member and an inner ring of the rollerholding member, between an exterior ring of the rolling bearing and thecylindrical member.
 4. The lens apparatus according to claim 1, whereinthe rolling bearing contacts the roller holding member, and the shaftmember contacts the cylindrical member.
 5. The lens apparatus accordingto claim 4, wherein the biasing force of the biasing member acts betweenan exterior ring of the rolling bearing and a contact portion of theroller holding member, between an inner ring of the rolling bearing andthe shaft member, and between the shaft member and the cylindricalmember.
 6. The lens apparatus according to claim 1, wherein the rollerholding member has an H shape on a section including the optical axis ina lens.
 7. The lens apparatus according to claim 6, wherein the rollerholding member has a first concave portion and a second concave portion,wherein at least part of the rolling bearing is disposed inside thefirst concave portion, and wherein at least part of the biasing memberis disposed inside the second concave portion.
 8. The lens apparatusaccording to claim 1, wherein the cylindrical member has a plurality ofconcave portions on a surface on which the roller rolls.
 9. The lensapparatus according to claim 1 further comprising a guide memberconfigured to guide the roller holding member so as to move the rollerholding member back and forth in a direction corresponding to a biasingdirection of the biasing member.
 10. The lens apparatus according toclaim 9, further comprising a holding plate that contacts the biasingmember, wherein the guide member and the press plate are fastenedtogether by a screw.
 11. An imaging apparatus comprising: a lensapparatus; and a camera body configured to hold an image sensor thatphotoelectrically converts an optical image formed via the lensapparatus, wherein a lens apparatus includes: a tripod mount; acylindrical member supported rotatably around an optical axis on thetripod mount; a roller housed in the tripod mount and including arolling bearing and a shaft member engaged with the rolling bearing; aroller holding member configured to rotatably hold the roller; and abiasing member configured to bias the roller against the cylindricalmember via the roller holding member.